Spin–Orbit-Induced Ising Ferromagnetism at a van der Waals Interface
Hideki Matsuoka, S. E. Barnes, Jun’ichi Ieda, Sadamichi Maekawa, M. S. Bahramy, Bruno Kenichi Saika, Yukiharu Takeda, Hiroki Wadati, Yue Wang, Satoshi Yoshida, K. Ishizaka, Yoshihiro Iwasa, Masaki Nakano
Abstract
Magnetocrystalline anisotropy, a key ingredient for establishing long-range order in a magnetic material down to the two-dimensional (2D) limit, is generally associated with spin–orbit interaction (SOI) involving a finite orbital angular momentum. Here we report strong out-of-plane magnetic anisotropy without orbital angular momentum, emerging at the interface between two different van der Waals (vdW) materials, an archetypal metallic vdW material NbSe2 possessing Zeeman-type SOI and an isotropic vdW ferromagnet V5Se8. We found that the Zeeman SOI in NbSe2 induces robust out-of-plane magnetic anisotropy in V5Se8 down to the 2D limit with a more than 2-fold enhancement of the transition temperature. We propose a simple model that takes into account the energy gain in NbSe2 in contact with a ferromagnet, which naturally explains our observations. Our results demonstrate a conceptually new magnetic proximity effect at the vdW interface, expanding the horizons of emergent phenomena achievable in vdW heterostructures.